Keith Waterhouse once wrote that Brighton looked like a town that was helping the police with its inquiries; no less memorably, Brighton resident Julie Burchill wrote that the simple word "esplanade" gave her a secret, sensual thrill. There's something of both these feelings in writer-director Rowan Joffe's bold, intelligent but flawed new version of Graham Greene's Brighton Rock, his noir tale of fear and sin amid the interwar racecourse gangs in Brighton. Here, it's updated to the 1960s world of running seaside battles between Mods and Rockers.

It's an intelligent and creative movie, not a masterpiece, but much better than some rather disobliging reviews have suggested, drawing less on the book than on the 1947 John Boulting film whose screenplay Greene co-wrote with Terence Rattigan. Fans of both, however, may be discontented with the way Joffe handles the ending, and the question of how to reveal what Greene's novel describes as "the greatest horror of all".

Sam Riley is teenage gangster Pinkie – at 30, it's a bit more of a stretch for Riley than for Richard Attenborough who was 23 when he played the part. Pinkie has precociously taken charge of a Brighton protection mob, and now presumes to challenge the pre-eminence of stately criminal grandee Colleoni, played by Andy Serkis, who lives in some style at the Continental hotel. But this looming turf war is complicated by other problems Pinkie is having: he has murdered an enemy gangster, Hale, and through an awful quirk of fate a seaside photographer snapped Pinkie's accomplice Spicer (Phil Davis) snarlingly menacing Hale as he was desperately attempting to cosy up to a waitress on her lunch-hour in the forlorn hope that this would deter his assailants.

This is the timid and mousy Rose (Andrea Riseborough) whom Pinkie must now seduce in order to get the ticket for that incriminating photo. He also intends to marry her, so that she will not be compelled to give evidence against him in any murder trial. Like Pinkie, she is a cradle Catholic, and Pinkie – gloomily and defiantly believing in his destiny in hell – consecrates their love to mortal sin. Helen Mirren plays Ida, the blowsy golden-hearted older woman who makes it her business to bring Pinkie to book. This movie ups her status, making her the manageress of the cafe where Rose is employed.

A sinking feeling asserts itself: could it be that our fallen, sinful world is just like Brighton? A tatty, cosmically temporary day-trippers' and dirty-weekenders' sort of place, whose promised pleasures always turn out to be fleeting and disappointing, leading you on to nothingness like a pier, giving way to desperate ennui in the face of death, lapping eternally like Brighton's deeply uninviting sea? Pinkie himself is drenched not merely with crime or wrongdoing but sin, yet it could be that in not murdering Rose but marrying her, however cynically or psychotically, Pinkie is the agent of mysterious divine grace – which does not redeem Rose or Pinkie, but at least clarifies for these terrified souls and for us, their witnesses, the lineaments of evil itself.

Any lover of the novel is bound to regret the way Joffe excises the famous beginning in which the victim Hale, in his character as "Kolley Kibber" is employed by a newspaper to stroll along the prom, giving cash prizes to any holidaymaker who recognises him, and placing time-coded cards in cafes and shops.

In the novel, Pinkie's mob lay a false trail of these cards after Hale's death to create an alibi, and worry that Rose will remember that someone other than Hale placed the one she found. A lot of flavour is lost in this film's beginning, though Joffe's "photo" device – taken from later developments in the book – here arguably creates a sharper and much more plausible anxiety.

Riley and Riseborough are both good, especially Riseborough, who brilliantly shows how Rose changes from being a child into a gangster's moll, embracing this fate while uneasily aware of its wrongness, and how it is founded on her complicity and self-deceit. The Mods and Rockers are a clever noir invention, a spectacle of disorder that Pinkie and his enemies can use as a cover for their own violence, and the youth gangs are also an interesting symbol for Britain's new fear and hatred of the young.

The problem is that these Mods and Rockers blur the issues: if the racecourse gangs are replaced by these youth gangs, it sits a little uncomfortably that Pinkie et al are not members of these tribes – they are still members of their own secondary set of gangs. By downplaying the horse-race setting, some of their drama and raison d'etre is lost.

This is still a bold and exhilarating picture, summoning up, in its own way, a chill seafront breeze of guilt and shame.